This invention related to electric bus duct and more particularly relates to an improved clamping structure for the bus bars which withstands blow-apart forces in the bus bars under short circuit conditions and therefore enables an external housing of the bus duct to be readily and economically fabricated and assembled.
State-of-the-art bus duct designs typically incorporate the external metal housing as an integral part of the bus bar support and clamping structure for increasing the strength of the clamping and supporting arrangement. Plug-in sections of bus duct which utilize straight flat bus bars spaced apart along their length have utilized corregated side members of the housing for engaging and supporting the opposite edges of the bus bar along the length of the bus stop. Another type of plug-in bus duct has wide flat insulated bus bars arranged with flat surfaces thereof in intimate contact with each other for reducing inductive losses, such bus bars being offset at plug-in intervals to provide necessary access for plug-in connection to the bus bars. Bus duct sections of the latter type typically have irregularly formed top and bottom housing members which are in contact with flat surfaces of the bus bars in the areas between the access openings and are offset similarly to the bus bars at the plug-in openings. Each of these approaches provides an external housing which has irregularly shaped surfaces which are costly to manufacture, require particular attention to clamping and securing the housing parts and bus bars together during assembly, are difficult to seal around when the bus duct is required to be installed through a wall of the building or the like, and which provide pockets on the upper external surface which accumulate water when used in outdoor applications.